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24 April 2024 |
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The R-Process Alliance: Discovery of a low-alpha, r-Process-Enhanced Metal-Poor Star in the Galactic Halo | Charli M. Sakari
; Ian U. Roederer
; Vinicius M. Placco
; Timothy C. Beers
; Rana Ezzeddine
; Anna Frebel
; Terese Hansen
; Christopher Sneden
; John J. Cowan
; George Wallerstein
; Elizabeth M. Farrell
; Kim A. Venn
; Gal Matijevic
; Rosemary F.G. Wyse
; Joss Bland-Hawthorn
; Cristina Chiappini
; Kenneth C. Freeman
; Brad K. Gibson
; Eva K. Grebel
; Amina Helmi
; Georges Kordopatis
; Andrea Kunder
; Julio Navarro
; Warren Reid
; George Seabroke
; Matthias Steinmetz
; Fred Watson
; | Date: |
4 Mar 2019 | Abstract: | A new moderately r-process-enhanced metal-poor star, RAVE J093730.5-062655,
has been identified in the Milky Way halo as part of an ongoing survey by the
R-Process Alliance. The temperature and surface gravity indicate that
J0937-0626 is likely a horizontal branch star. At [Fe/H] = -1.86, J0937-0626 is
found to have subsolar [X/Fe] ratios for nearly every light, alpha, and Fe-peak
element. The low [alpha/Fe] ratios can be explained by an ~0.6 dex excess of
Fe; J0937-0626 is therefore similar to the subclass of "iron-enhanced"
metal-poor stars. A comparison with Milky Way field stars at [Fe/H] = -2.5
suggests that J0937-0626 was enriched in material from an event, possibly a
Type Ia supernova, that created a significant amount of Cr, Mn, Fe, and Ni and
smaller amounts of Ca, Sc, Ti, and Zn. The r-process enhancement of J0937-0626
is likely due to a separate event, which suggests that its birth environment
was highly enriched in r-process elements. The kinematics of J0937-0626, based
on Gaia DR2 data, indicate a retrograde orbit in the Milky Way halo; J0937-0626
was therefore likely accreted from a dwarf galaxy that had significant
r-process enrichment. | Source: | arXiv, 1903.1480 | Services: | Forum | Review | PDF | Favorites |
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